Hi. Congratulations on your ongrowing collection. There is no Clymer manual for the 1989 - 1994 KDX200's. The OEM service manual (not the owner's manual) is it. The only Clymer manuals are for 1979 - 1980 KDX's and 1983 - 1988 KDX200's. Here's the part numbers for a 1991 KDX200:
1991
KDX200-E3
Owner's Manual, 99920-1543-01
Service Manual, 99924-1114-02 (current)
Assembly & Preparation Manual, 99931-1064-02
Assembly & Preparation Supplement Manual, 99931-1220-01
On your secon question, the 1989 - 1994 models are all very similar, except for the forks on the 1993 and 1994 KDX200's (USD cartridge instead of the 1989 - 1992 conventional damping rod forks). Look for UFO plastic. Maier makes some too, but UFO is better IMHO.
Good luck with it.